Xinhua wraps up the situation so far this season: H7N9 cases persist through winter.
New cases of human infections of the H7N9 virus have been reported daily across the country as winter continues.
On Friday, three cases were confirmed in Guangdong and one case was confirmed in Hunan. The cases in Guangdong are aged from 48 to 62, while the one in Hunan is a 21-year-old woman.
The patient had contact with live poultry before she came down with flu symptoms and sought medication. She is now receiving treatment in the provincial capital of Changsha.
In December, five cases of human H7N9 infections were reported, according to the National Health and Family Planning Commission. The number rose to 110 from Jan 1 to Jan 28, China Central Television reported.
Feng Zijian, deputy head of the Chinese Center for Disease Control and Prevention, said it's possible that the incidence of human cases of the bird flu will grow as the weather gets colder, considering there were few new cases from July to October.
However, it's hard to predict whether the virus discovered only less than a year ago will become less active over the summer this year as other strains of bird flu and seasonal flu have in the past, he added.
South China's Guangxi Zhuang autonomous region reported on Jan 29 its first human H7N9 infection of a 56-year-old woman.
On Feb 4 and Feb 5, the region's health authorities said a 41-year-old woman and her 5-year-old son were infected. The woman showed flu symptoms on Jan 27 in Zhongshan, neighboring Guangdong province, and is now under emergency treatment in Guangxi, said its health bureau.
Guangdong province reported new human cases of the virus every day from Feb 1 to Feb 7. The cases broke out in Shenzhen, Huizhou, Zhongshan, Zhaoqing, Yangjiang, Foshan and Guangzhou. By Thursday, a total of 55 people were infected in the province, including 12 deaths.
East China's Jiangsu province reported three new cases in February. Since the new year, there have been 11 cases of infection in the province, of which one died, according to the provincial health department.
In northern China, the Beijing health and family planning commission reported a case on Thursday in which a 73-year-old former poultry butcher and salesman was in "extremely critical condition".
This is the second case of human H7N9 infection in Beijing this year. The first case, a man diagnosed on Jan 23, died on Jan 30 despite emergency treatment.
However, He Jianfeng, chief expert of Guangdong's center for disease control and prevention, said the increase in new cases doesn't indicate a change in the virus' toxicity.
"From our monitoring, the death rate caused by the virus and the way it's transmitted remains the same with that in the first wave of infection from March to May in 2013, where cases were concentrated in eastern China. Most of the people infected or who have died from the virus are still people older than 50," he said.
Researchers in Shanghai, where the first diagnosed human H7N9 infections occurred, have developed a genetic vaccine for the virus that has proved effective on laboratory mice, and are applying for its clinic tests, Shanghai Youth Daily reported on Friday.
"There hasn't been a vaccine against H7N9 that has officially passed clinical tests in China. If this virus passes the clinical tests, we will be able to use the technology to ward off the virus immediately if it ever mutates, as it does during transmission from human to human effectively," said He.